Process for preparing chloro-polysiloxanes

ABSTRACT

PROCESS OF PREPARING COMPOUNDS OF THE THE GENERAL FORMULA   R-SI(-CL)A-O((3-A)/2)   WHEREIN A=0.5 TO 991 AND R IS HYDROGEN, CHLORINE, ALKYL OR ARYL, BY SUBJECTING SILANES OF THE GENERAL FORMULA RSIC13 TO HYDROLYSIS WITH TERTIARY ALCOHOLS AS HYDROLYZING AGENTS. THE TERTIARY ALCOHOL IS ADDED IN DROPWISE MANNER TO THE SILANES AT TEMPERATURES BETWEEN ABOUT 10*C.-150* C., PREFERABLY IN THE PRESENCE OF AN INERT SOLVENT. LESS THAN 0.9 MOLE OF TERITARY ALCOHOL PER MOLE OF SILANE ARE USED. UNREACTED SILANE AS WELL AS T-ALKYLCHLORIDE, WHICH IS FORMED AS BY-PRODUCT, AND THE SOLVENT ARE REMOVED BY DISTILLATION. THE COMPOUNDS ARE HYDROPHOBING AGENTS FOR A VARIETY OF PURPOSES AND STARTING MATERIALS FOR HARDENERS OF SILICONE RUBBERS. THE PROCESS RESULTS IN THE FORMATION OF NOVEL COMPOUNDS OF THE FORMULA   R-SI(-CL)A-O((3-A)/2), AND (R-SI-O(1.5))G,   (R-SI(-CL)2-O(0.5))G, (R-SI(-CL)-O(1.0))B   HAVING AN AVERAGE MOLE WEIGHT OF 600-2000 WHEREIN A= 0.5-0.9, G IS GREATER THAN H, G AND H ARE GREATER THAN ZERO, AND R IS HYDROGEN, CHLORINE, ALKYL OR ARYL.

United States Patent Olfice 3,687,642 Patented Aug. 29, 1972 3,687,642 PROCESS FOR PREPARING CHLORO-POLYSILOXANES Gotz Koerner, 126 Kantorie, 43 Essen, Germany, and Gerd Rummy, 27 Barkhorstrucken, 43 Essen-Werden, Germany N Drawing. Filed May 19, 1971, Ser. No. 145,047 Int. Cl. C01!) 33/00, 33/20; C07f 7/08 U.S. Cl. 423-342 8 Claims ABSTRACT OF THE DISCLOSURE Process of preparing compounds of the general formula Rsi-o wherein a=0.5 to 1.1 and R is hydrogen, chlorine, alkyl or aryl, by subjecting silanes of the general formula RSiCl to hydrolysis with tertiary alcohols as hydrolyzing agents. The tertiary alcohol is added in dropwise manner to the silanes at temperatures between about 10 C.-150 C., preferably in the presence of an inert solvent. Less than 0.9 mole of tertiary alcohol per mole of silane are used. Unreacted silane as Well as t-alkylchloride, which is formed as by-product, and the solvent are removed by distillation. The compounds are hydrophobing agents for a variety of purposes and starting materials for hardeners of silicone rubbers.

The process results in the formation of novel compounds of the formula and having an average mole weight of 600-2000 wherein a: 0.5-0.9, g is greater than h, g and h are greater than zero, and R is hydrogen, chlorine, alkyl or aryl.

FIELD OF INVENTION The invention relates to a process for preparing compounds of the general formula be inert, i.e. they may be substituted by groups which are free of acidic H atoms.

BACKGROUND INFORMATION AND PRIOR ART The hydrolysis of halogen-silanes with tertiary alcohols, especially t-butyl alcohol, has been known for along time; it is, for instance, described in W. Noll Chemie und Technologie der Silicone 2nd edition, 1968, page 173. t-Alkylchloride, e.g. t-butylchloride, is formed as a byproduct of the reaction.

German Auslegeschrift 1,807,410 discloses a process for preparing halogen siloxanes of the formula wherein R is hydrogen, alkyl or aryl, preferably methyl or phenyl, X is chlorine or bromine, a=0 or 1, and b=1, 2 or 3, and (a'+b) :2 or 3, preferably 3. This process is characterized by the dropwise addition of about b moles of tertiary alcohols to a mixture of one mole silane of the formula R 'SiX and 2b to 5b moles silanes of the formula (CH SiX, at temperatures below 40 C., if desired with simultaneous passage of HX.

The silane reaction mixture contains large amounts of silanes of the formula (CH SiX, to wit of monofunctional silane. In this manner it is prevented from the very outset that hydrolysis of the silanes of the formula R SiX present in the silane mixture, results in the formation of gel-like hydrolysis products.

The hydrolysis of chlorosilanes of higher functionality, particularly of triand tetrafunctional chlorosilanes, or of mixtures containing such silanes, presents a very serious problem. The formation of gel-like reaction products is then always a danger.

SUMMARY OF INVENTION It is therefore a primary object of the present invention to provide a process of preparing chloropolysiloxanes in which such gel formation is positively avoided.

It is also an object to provide novel compounds useful as hydrophobing agents, e.g. for leather, textiles and the like and protective coatings for buildings, as well as starting materials for hardeners for silicone rubbers.

Other objects and advantages of the invention will become apparent from the detailed description below.

It has surprisingly been found that by the use of tertiary alcohols and special reaction conditions, trifunctiom al halogen silanes can be hydrolysed to well-defined liquid or liquefiable chloropolysiloxanes without the undesirable gel formation taking place.

The process of the invention is characterized by first introducing the silanes into a reaction vessel and adding the tertiary alcohol dropwise at temperatures between 10 and C., if desired in the presence of an inert solvent, the amount of tertiary alcohol per mole of silane being less than 0.9 mole preferably 0.5-0.125 mole, and distilling off the unreacted silane with the t-alkylchloride formed as by-product and the solvent, if used.

As tertiary alcohol it is preferred to use one with 4-8 C atoms, particularly t-butanol.

The process according to the invention may be illustrated by the following reaction mechanism:

eRSiCl: t-ROH wherein c=l.l8 R=t-alkyl with 4-8 C atoms a=0.5-l.l R=H, C1, or alkyl or aryl which may, if desired be substituted. In the reaction, new compounds are formed having the general formula with a mean moleweight of 600-2000, wherein R and a have the above indicated meaning.

The above formula indicates the average composition of the reaction product. The amount of individual species depends on the reaction parameters, especially on the temperature and the ratio of silane to tertiary alcohol in the reaction. In the hydrolysis at room temperature, siloxanes are formed, primarily, with a being less than 1,

mostly between 0.5 and 0.9. These siloxanes correspond to wherein d e and f, and d, e, f O.

These siloxanes are not in equilibrium as far as the polymer distribution is concerned. Upon addition of a slight amount of an acidic equilibration catalyst, such as sulfuric acid, a gel is formed immediately.

Contrary to this hydrolysis at room temperature, when reflux temperature is applied, or, when the boiling point of the silanes to be hydrolysed lies above 100 C., when working at 100 C., siloxanes will be formed in which the value a will be quite close to 1, if the use of inert solvents is avoided. The structure of these products was established by NMR spectroscopy. This showed that these siloxanes correspond to the formula [RS|i-O1.0] 01 h These are cyclic siloxanes, which explains that the ratio GlzSi, that is to say, the value a is approximately 1.

The mole ratio of silane:tertiary alcohol is likewise important for the compositions of the reaction product. In general, the value a decreases with increasing amounts of the tertiary alcohol. In a certain mole ratio, a range is reached in which gel-like residues are formed. This gel forming limit value lies, for instance, in the reflux temperature hydrolysis of methyltrichlorosilane between 0.5 and 0.66 mole of t-butanol per mole of silane. However, the limit value for gel formation may be extended by the use of an inert solvent, e.g. carbontetrachloride, to a range in which the process may still be carried out within the limits defined in the claims. Inert solvents are for this purpose such solvents which do not react with chlorosilane and which do not belong among Lewis bases such as ether or tertiary amines.

Whereas the hydrolysis products of methylchlorosilane are liquid, those of phenyltrichlorosilane are solid. However, the latter are soluble in inert solvents and they are liquid at elevated temperature, e.g. 200 C., therefore, they are no gels. In the hydrolysis of hydrogentrichlorosilane it is surprising that the hydrogen bound to silicon remains intact although it is sensitive to hydrolysis. In some cases, eg in the reflux hydrolysis of SiCl the yield in non-volatile chlorosiloxanes is comparatively small, if distillation is carried out at the bridge. In such cases the use of a distillation column is advisable.

The compounds made according to the invention in which R= CH or long-chain alkyl with 12-18 C atoms, are excellent hydrophobing agents, particularly for surfaces of silicates. The chlorine atoms then react with surface bound hydroxyl groups or with adsorptively bound water. This property renders the compounds according to the invention useful as protective agents for building structures. They are furthermore excellently adapted for hydrophobing other materials, such as leather, textiles and the like.

Another application is the use of the compounds as starting materials for the production of hardeners for silicone rubbers hardening at room temperature with admission of atmospheric humidity, the Cl-atoms of the compounds of the invention being then exchanged for acetoxy-, alkylamino, amidoor oxim groups.

The compounds according to the invention form, when undergoing hydrolysis condensation, brittle silsesquioxanes. However, when the inventive compounds are used as building blocks for the preparation of mixed polymers, more or less elastic, impact-resistant polymers will be formed depending on the kind of said mixed polymers, when they are subjected to hydrolysis condensation. Particularly interesting are in this connection such mixed polymers which contain as organic building block lightly cross-linked pre-polymers or prepolymers without cross-linkage, e.g. linear polyesters of aliphatic or hydroaromatic dicarboxylic acids with terminal C-OH-groups which react with the SiCl-groups of the compounds of the invention by SiOC-linking. Of course, in this reaction only a small number of the SiCl-groups should take part, whereas the remaining ones are cross-linked in the subsequent hydrolysis condensation. Instead of the organic pro-polymers organic silicon compounds may be used, e.g. a, w-dihydroxypolydimethylsiloxane.

The process of the invention and the properties of the novel compounds made shall now be described more fully in a number of examples which are given by way of illustration but not of limitation. Many changes in the details can be made without departing from the spirit of the invention.

Example 1 A three-necked flask is first charged with 598 g. (4 mols) of methyltrichlorosilane, to which 74.1 g. (1 mol) of t-butanol are added drop by drop within 3 hours at room temperature, while stirring. Stirring is then continued for two more hours at room temperature and for another hour at reflux temperature. The product is then subjected to distillation with use of a distillation device without a column at a bath temperature of 210 C. at normal pressure, whereby volatile substances are eliminated. The residue totalling 70.3 cor-responds to the formula CHaS i .18

Clara determined by the hydrolytically found Cl-value.

The values found by means of elementary analysis conform well with the above. Percentages are given by weight.

Theoretically calc. (percent): Si, 32.7; C, 14.0; H, 3.5. Found (percent): Si, 32.2; C, 13.8; H, 3.5.

The yield in hydrolysate, calculated on t-butanol used as hydrolyzing agent, was The viscosity of the product was 192 op. (20 C.). The mole weight was 1200 determined kryoscopically. In the infrared range the product has a wide band at 1026 cmr This band corresponds ot a SiOSi-stretching vibration of a strained cyclic siloxane. Bands which could indicate a content in t-C H O-Si-groups were not observed in the infrared spectrum. In the NMR-spectrum, taken with a Varian 1 unit A 100, 3 peaks were obtained at 9.74r, 9.461 and 9.171- -(peak for tetramethylsilane= 10r). The peaks were in an area ratio 113:36:50. They belong to the groupings.

Corresponding to the first formula shown in col. 3, the ratio d:e:f=l13:3 6:50. This corresponds very well to a value for a (CluSi ratio) of 0.683, which conforms to the value 0468 determined from the Cl-content.

Example 2 Working in accordance with Example 1, but with the use of 1196 g. (8 mols) methyltrichlorosilane per 74.1 g. (1 mol) t-butanol, a product having the following formula.

E mu Glam 1 Of Varian Associates of Palo Alto, Calif.

was obtained. The yield was 59.2 g. that is 78.2% of the theory calculated on t-butanol used. The viscosity of the product was 165 cp. Cryoscopically a mole weight of umn at 210 C. bath temperature under normal pressure. The residue-91 g.corresponded to the formula CH; 1300 was found. In the IR-spectrum a wide band was ob- I o served at 1026 cmr which corresponds to a stretching vibration of a strained cyclic siloxane. In the NMlK-speca? azasii dtsr attire; trea ies :2 a of or} 106'5 3'4 5 Corres bndi n to the first formula in col 3 butanol used The vlscoslty was the molar weight a This corresponds to cryoscopically determined was 930. With the formula given value for a -ratio) of 0.701 which conforms well the figures.found by elementary analysts conformed t th value 0 7 1 determined froni the Cl-content Theoretlcany calculate? (percent): 29'7; 12'7;

0 e 3.2. Found (percent): s, 29.3; c, 12.8; H, 3.2.

Example 3 In the infrared spectrum the Si-O-Si stretching vibration at 1026 cm." which corresponds to a strained cyclic In analogy to Example 1, 846.4 g. (4 mols) or 423.2 g. 15 (2 mols) phenyltrichlorosilane were reacted with 74.1 g. slloxane was mlssmg: Also In the R' P no bands (1 m 01) t butanol In that case the volatile components could be observed WhlCh would have indicated the presence were distilled off at 210 C. bath temperature and 18 of tlC4H9 OS1'grups In the NMKspectwm taken with mm. Hg. Obtained were 134.8 g. or 120.5 g., respectively, Vanan A 3 Peaks were optamed at of siloxanes solid at room temperature, but liquid at (Peak for tetralnetylflane=lofl i peaks app 210 C. and soluble in toluene. The analytically deter- Peared m the area who correspondmg to group mined composition corresponded to the formulas mgs e s CaHs (Ill Si l us or 20 CHaSiO CH3-S|i-O1 0 and CH3S|IO0 5 Gloss 010.00 01 C1 The yields were therefore 93.2 that is 99% of the theory, The Product therefore has the formula calculated on t-butanol used. 01 OH aSiOi 5131: CHaS i0o.n I: a I Example 4 v I 01 a Working in analogy to Example 1, but using 448.5 g. C1 (3 mols) methyltrichlorosilane and 74.1 g. (one mole) t-butanol, a gel-like residue was obtained. When, however T product was distilled at 1 mm. Hg in a falling film 748 g. carbontetrachloride were added during the hyevapofatofdrolysis, a siloxane f h form la The following fractions were obtained:

T BLE CHaSiOi.2s5 A I a-Value or Clom Telfuperature of the evaporator gilfiell; rlzlztio M0112 surace $1878 111 S138 we1g is obtained having a viscosity of 280 cp. and a cryoscopi- 40 100 16 8 0 99 610 cally found mole weight of 650. 150. 11:11:: 15: 2 1: 00 680 22a: 5-2 5-22 .5212 Example 5 300 11:6 1100 1:300 Into a three-necked flask 598 g. (4 mols) methyltrichlorosilane were introduced and heated until reflux set in. iiz was value was and the mole Then 74.1 g. (one mole) t-butanol were added drop by Welg t E I 6 drop, while stirring, within 3 hours, with the reaction prod- Xamp e uct kept boiling under reflux. Subsequently, the product In analogy to Example 5, several silanes were hywas refluxed for three more hours and then all volatile drolyzed with t-butanol at reflux conditions or 100 (1., material distilled off over a distillation device without colrespectively. The results are tabulated in Table II.

TABLE II Moles silane Viscosity, c'p, Yield calc, Silane per 1 mole Composition (20 0) (mole 0n t-butaused t-butanol Conditions of product weight) n01, percent Remarks CHaSiCl3 s Reflux (EH3 34.9 (920) Cli-uiSiOo-n5 CH SiCl3 2 ..do Cl iia 38.6 (940) 98 O-Dll 'S Ol-fl05 CHaSiCla l 5 .d0 (3H3 Gel C1si0 CHaSiCl; 1 1 ..do CH3 225 (763) 87.7 434 g, 0014 added per mole I tbutanol, Cln.sSiOi.g

CsH5SiC13 4 100 0 Com (1) 96.7 Distilled at 210 0, bath temperature and 18 mm, Hg, Clo-wSiOi.oos

HSiCl3 4 Reflux 1?: 11.7 (790) 96.5 H,1 f201u7nd, 1,20%; H, 02.10,,

C11.1-Sl0u.95 I D,

sic].-- 4 do 01 14.7 (880) 99.8 Column-distillation,

1 At room temperature solid.

What is claimed is:

1. In a process of preparing compounds of the formula c1, 2 wherein a=0.5 to 1.1 and R is hydrogen, chlorine, alkyl or aryl, by subjecting silanes of the general formula RSiCl wherein R has the above meaning, to hydrolysis with tertiary alcohols as hydrolyzing agents, the improvement which comprises first introducing said silanes into a reaction vessel and adding thereto the tertiary alcohol in dropwise manner at temperatures between C. and 150 C. the amount of tertiary alcohol per mole of silane being less than .9 mole and thereafter removing by distillation the unreacted silane together with t-alkylchloride which is formed as a Joy-product.

2. The improvement according to claim 1, wherein the alkyl or aryl is substituted.

3. The improvement according to claim 1, wherein the hydrolysis is carried out in the presence of an inert solvent which is removed by distillation together with the unreacted silane and the t-alkylchloride.

4. The improvement according to claim 1, wherein the amount of the tertiary alcohol added to the silane is between 0.5 and 0.125 mole per mole of silane.

5. The improvement according to claim 1, wherein the tertiary alcohol used has a chain length of C to C 6. The improvement according to claim 5, wherein the tertiary alcohol is t-butanol and the silane is YSiCl wherein Y is hydrogen, methyl, ethyl, propyl, butyl or phenyl.

8 7. A liquid or liquefiable compound of the general formula 4.0mm-

8. A liquid or liquefiable cyclic siloxane of the general formula having a mean mole weight of 600 to 2000, wherein R stands for hydrogen, chlorine, alkyl, aryl, substituted alkyl, or substituted aryl, and g is greater than it, and g and h are greater than zero.

References Cited UNITED STATES PATENTS 3,432,538 12/1969 Curry 260-48.2 E 3,484,468 12/1969 Curry 260-4482 E 3,101,361 8/1963 Brown et a1. 23366 DELBERT E. GANTZ, Primary Examiner P. F. SHAVER, Assistant Examiner US. Cl. X.R.

106-13; 26046.5 R, 448.2 R, 448.2 E 

